A rotary press has at least one upper and one lower pressing station with at least one compression roll. The compression rolls act on the upper and lower punch in order to press the powdered material filled into die holes. The compression rolls are typically mounted in a rotational manner in a stable bearing component. Because the thickness of as for example a tablet is predetermined, a corresponding setting of at least the upper compression roll is required in order to attain the desired thickness dimension (base height). Therefore, to be able to produce different pellet thicknesses on a rotary press, it is known to make the bearing component vertically adjustable in height using an adjustment drive and an adjustment gear. Because the height of the compression roll must attain a very precise setting, the gear ratio of the adjustment gear is very high. Thus, a large number of rotations of a rotating drive motor are necessary in order to make a millimeter adjustment. Therefore, it takes considerable time to move a compression roll to another dimension.
It is also known to use rotary presses for producing multilayer tablets. The first layer is pressed in a first pressing station, before the second layer is filled. With three layers, the second layer is also pressed in a further pressing station before the complete compression of all three layers takes place in a third pressing station. For the final compression, typically two compression rolls are used after each other (pre-compression and main compression station).
During production startup for a new multilayer tablet, samples are withdrawn for the individual layers. Such sampling is necessary; in particular, to determine the effects on the filling, the individual layers and with it, the portion of active agent, before the production of multilayer tablets is started. However, because only a light pressing occurs in each case at the respective pressing stations for the first layers of a multilayer tablet, in each case, it is not possible to lift the layer out of the die hole and strip it off without destroying it. Therefore, it is known, through adjustment of the corresponding compression roll to press the layer being sampled with more force, if it is to be produced individually and ejected. Depending on the requirement of the compression force, the compression roll must be moved by a desired distance. During the adjustment of the compression roll while withdrawing samples, the pressing force increases only very slowly due to the slow travel speed of the compression roll. The drive motor requires a multiplicity of rotations in order to move the compression roll, for example, by 1 or 2 mm. However, this slow movement speed affects the filling of the layer sample and leads to an erroneous layer sample weight. The production of production tablets is otherwise based on the erroneous layer weight and can lead to incorrect concentrations of the active agent.
Therefore, the object of the invention is to create a pressing station that enables rapid adjustment of the compression roll for withdrawing samples.